1. Field of the Invention
The invention relates to gusset forming machines and processes and, more particularly, relates to a machine and process for forming gussets used in the edges of expandable folders and the like.
2. Discussion of the Related Art
Many folders, containers, and the like are expandable from a relatively flat state for storage or shipment to a working state for storing articles such as papers. Such expansion is typically enabled by forming the edges of the folders or other articles from pleated gussets each having an effective width which can be selectively varied by alternately collapsing and straightening out the gusset in an accordion-like fashion. Such gussets are typically expandable from a thickness of 1/8" or less to several inches or more.
Gussets of the type discussed above are typically formed by bending paper or cardboard blanks along longitudinal lines so that the resulting gusset is foldable in opposite directions on opposed sides of each line thus permitting the gusset to collapse onto itself. The blanks for the gussets may be scored in the desired locations to facilitate folding.
Heretofore, gussets have usually been formed either by forming the blank by hand or with manually operated knives. These prior art processes are relatively labor intensive and thus are relatively time consuming and expensive. They are also relatively unreliable because they are dependent upon the skills of the individual laborer who may make mistakes, rendering the completed gusset ineffective or useless.
These problems are especially critical when a gusset is formed which extends along the sides and ends of the folder or other article incorporating the gusset. For proper folding, the corners of the gusset must be formed such that the bottom edges of the valleys on one side of each corner are aligned with and extend into the valleys formed between the adjacent ridges on the other side of each corner. Producing such a gusset manually or even via a manually operated machine typically requires at least three separate forming steps--one for each side--and is thus very time consuming. Any misalignment of the ridges and valleys of the adjacent sides may seriously degrade the effectiveness of the gusset. While this problem may be alleviated somewhat by employing scored gussets, it cannot be eliminated entirely. Even those machines which are capable of folding gussets are incapable of forming the corners. The corners must therefore be formed manually in an operation which results in adjacent plates extending in alternate directions at the corners because the pushing forces for adjacent pleats are imposed from adjacent sides, e.g., top and right side, of the gusset. The resulting corner is not only aesthetically unappealing but also tends to trap dust between alternate folds.